How can I blend different textures on a landscape?
From what I read, i think your asking about how you can have 2 image textures and just smack them onto the same plane/object for landscaping scenes. Now this is some what my specialty and passion as it is what i do nearly everyday. So for example i will use Grass and dirt(soil) to explain. In the real world, grass needs dirt to survive. So in order to have an effective scene which captures the audience you need to have a base plain with 1 texture, (Dirt) and use a particle system to apply the grass patches where you want. To add more effect instead of using a normal map, use a displacement map to show small details like rocks and particles. And apply your grass. It will give you a great effect with lots of control and will also open up opportunities for animation of the grass when wind interferes with it. I hope this helps you with an understanding that some things shouldnt be just textures and that they need their own objects.

https://www.youtube.com/watch?v=eshOzshjt90
Here is a tutorial of what I mean.